Operation of high-speed passenger boats in rough water presents many engineering challenges. When boats having conventional U-shaped or V-shaped hulls are operated at high speed over large waves, many problems are encountered, including severe pounding of the hull bottom on the waves, spraying of large amounts of water over the bow and onto the deck, and instability negotiating sharp turns.
In an attempt to eliminate these problems, prior inventors have devised various types of hydroplaning boats having hulls which ride above the water surface, reducing surface friction and spray. Most hydroplanes employ submerged hydrofoils or full length tunnels or other devices to lift the hull out of the water.
However, such prior art boats retain significant disadvantages which render such boats unsuitable for large-scale commercial passenger and freight use. In particular, prior art boats typically operate with very low planing weight. To achieve hydroplaning, prior art boats employ expensive, lightweight, fragile hulls unsuitable for carrying commercial cargo or passengers. Such boats are usually capable of efficiently carrying, at maximum, 45 pounds per engine horsepower, including the weight of hull, engine, and crew.
Prior art hydroplaning hulls also cause severe surface-hull pounding, even in moderately rough water, which pounding is uncomfortable and in many cases dangerous.
Under certain conditions prior art boats, having U-shaped or V-shaped hulls constructed with forward water lines (or lines of immersion) curving inward toward a vertical stem or keel line, are highly susceptible to "tripping." Also, waves are generated by V-shaped hulls; the deeper the V, the heavier the wave. Tripping is a dangerous condition encountered when a boat is turned sharply in one direction; the boat slides laterally over the water surface in a direction opposite the direction of the turn, creating a high risk of capsizing.
Finally, prior art boat designs with inward curving forward water lines typically have continuously wet hulls during operation, and throw water onto the deck at low or moderate speeds, and in some cases, even at high speeds.
The present invention resolves the above problems by providing a keelless inverted "U" boat hull having upright, nearly vertical sides from the chines to the at-rest water line, deeply, outwardly-curved hull sides from the at-rest water line to the gunwales, and propulsion means (surface piercing out-drives, stern drives, outboard motors, or water jets) operative to guide the boat without a rudder, or bottom appendages thereby lessening drag and promoting stability during sharp turns. The curved dead rise sides of the tunnel from the chines to the tunnel apex generate a wake and spray that is captured in the tunnel. The air, solid wake water and spray proceed aft toward the stern, hydrodynamically elevating the hull in a lateral fashion fore and aft.
Prior inventors have addressed similar problems, but without including all the features of the present invention. For example, several prior art patents disclose boat hulls having inverted, concave surfaces, but these hulls generally include keels or rudders. For example, U.S. Pat. Nos. 804,269 (Ross), 815,187 (Manker), and 4,192,248 (Moyer) show boat hulls having inverted-U, concave bottom surfaces, but all these prior patents include keels or rudders. Further, U.S. Pat. No. 2,735,392 (Cox) shows a boat hull having an upwardly arched bottom and a plurality of keels provided with rudders and propellers. These prior art references do not permit rapid, smooth hydroplaning and exclude other features of the present invention.
Other prior inventions provide submerged planing surfaces, causing substantial surface friction which is circumvented by a boat hull according to the present invention. For example, U.S. Pat. No. 3,709,179 (Payne) includes submerged planing surfaces 22 interposed between the inner chine and the outer chine.
U.S. Pat. No. 2,366,590 (Brownback) shows a speed boat having an inverted-U forward hull portion and an aft hull portion including chine line 1B and keel 1D. The inverted U-hull of Brownback terminates at a point midway between the bow and stern such that a flat portion of the hull bottom and the keel, remain submerged and do not hydroplane.
Similarly, U.S. Pat. No. 1,886,507 (Wehr) shows a boat hull having an inverted concave hull and flat sides 11 and 12. These sides do not effectively prevent tripping. Further, Wehr shows keels 16 and 17, and chine lines 18 and 19, which create submerged planing surfaces. These surfaces cause significant friction between the hull and the water surface.
Thus, the prior art is deficient and does not provide a hydroplaning boat hull having all the features of the present invention. Specifically, the prior art does not include a boat hull constructed with an inverted U-shaped hull bottom tunnel, flared hull sides which are outwardly curved at a deep arc, and rudderless construction. Further, no prior art references disclose a boat hull having the aforementioned structure which is capable of smoothly and rapidly assuming a hydroplaning position without squatting at stern during acceleration, or use of hydrofoils, which reduces wave pounding, which is navigable in fouled water, which substantially reduces wake or water sprayed aboard, and which avoids "tripping" when navigated through sharp turns. Consequently, commercial freight and passenger boat operators, as well as pleasure boat enthusiasts, would find useful a boat hull according to the present invention which avoids all the aforementioned disadvantages of the prior art.